1. Field of the Invention
The present invention relates generally to a heat dissipation device and a manufacturing method thereof, and more particularly to a fixing structure for a heat dissipation device. The fixing structure can be disposed on the heat dissipation device without damaging the main body thereof. Accordingly, the working fluid is prevented from leaking out of the chamber of the heat dissipation device so as not to affect heat transfer efficiency of the heat dissipation device.
2. Description of the Related Art
There is a trend to slim the electronic devices. To catch up this trend, the electronic components of the electronic devices must be miniaturized with the electronic devices. While reducing the size of the semiconductors that compose the electronic components, the electronic devices are still required to have advanced performance. In this case, it has become a critical topic how to efficiently dissipate heat generated by the electronic components.
A conventional heat spreader is used to face to face transfer heat by a large area. The heat spreader is different from a heat pipe that transfers heat point to point. The heat spreader is applicable to an electronic device with a narrower space.
The conventional heat spreader is connected to a substrate for transferring the heat generated by a heat generation component on the substrate. Conventionally, multiple through holes are formed in four corners of the heat spreader to avoid the chamber thereof. A copper pillar with an inner thread is fitted through each through hole. The substrate is formed with at least one perforation in a position where the copper pillar of the heat spreader is positioned. A fastening member is screwed through the copper pillar and the perforation to affix the heat spreader to the substrate. In such a fixing manner, the copper pillars are arranged in four corners of the heat spreader and spaced from the heat generation component by a considerably long distance. Therefore, after affixed to the substrate, the heat spreader can hardly tightly attach to the heat generation component. This will lead to thermal resistance. To overcome this problem, in another conventional heat spreader, the copper pillars are directly arranged in the heat spreader in a position near the heat generation component. In this case, the copper pillars directly pass through the chamber of the heat spreader to increase assembling tightness and avoid thermal resistance. However, after the copper pillars penetrate through the chamber of the heat spreader, the chamber is no more vacuumed and will lose its airtightness. Moreover, the copper pillars that pass through the chamber will interrupt the flowing path of the working fluid contained in the chamber and hinder the working fluid from smoothly flowing. This will deteriorate heat transfer efficiency or even cause leakage of the working fluid. Under such circumstance, the heat spreader will lose its heat transfer effect.
Please refer to FIGS. 1a and 1b. U.S. Pat. Nos. 7,066,240, 6,302,192 and 7,100,680 disclose a heat spreader structure 5 including a main body 51 composed of a first flat board 511 and a second flat board 512. An outer protrusion section 513 is formed along the periphery of each of the first and second flat boards 511, 512. The outer protrusion sections 513 are connected with each other to define a closed chamber 514. A recess 5111 is formed on the first flat board 511 and distal from the outer protrusion section 513 and connected to the second flat board 512. A perforation 52 passes through the recess 5111 of the first flat board 511 and the second flat board 512. The recess 5111 has an annular outer surface 5112 connected to a corresponding annular peripheral surface 5121 of the second flat board 512, whereby the perforation 52 is isolated from the main body 51. A spacer section 53 extends into contact between the first and second flat boards 511, 512. A capillary fiber structure 54 is disposed in the closed chamber 514. By means of the recess 5111, a support structure is provided for the heat spreader to achieve an airtight effect. However, due to the recess 5111, the internal room for vapor-liquid circulation of the working fluid in the chamber of the heat spreader is greatly minified. Also, due to the recess, the contact area between the heat spreader and the heat source is greatly reduced. This lowers the heat transfer efficiency.
According to the above, the conventional heat spreader has the following shortcomings:    1. The conventional heat spreader is likely to have the problem of thermal resistance.    2. The heat dissipation area of the conventional heat spreader is smaller.    3. The heat transfer efficiency of the conventional heat spreader is lowered.